Improvement in rock-drilling engines



P. s. BUCKMINSTER.

ROCK-DRILLING ENGINE.

No. 186,923. I Patented Feb.6,1877.

Unrrnn PRESCOTT S. BUCKMINSTER, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOROF ONE-HALF HIS RIGHT TO IRA P. RANKIN AND GEORGE W. FOGG, OF

SAME PLACE.

IMPROVEMENT IN ROCK-DRILLING ENGINES.

Specification forming part of LettersPatent No. 186.923, dated February6, 1877; application filed June 30, 1875.

' operating the valve which admits the steam or air to, and exhausts thesame from, the cylinder of a rock-drilling engine; and, secondly, thisinvention relates to a new and improved device for automatically turningthe drill at each stroke of the piston, so that the face of the drillmay never strike twice in the same place.

In the accompanying drawing, Figure l is a longitudinal section ofcylinder, valve and chest, piston and rod, sleeve, 850. Fig. 2 is a planof piston and sleeve, showing slots in same, which slots operate inconnection with the valve-tripping device. Fig. 3 is a view of sleeve,piston, 8220., partly in section, illustrating the device for turningthe drill. Fig. 4 is a plan, showing the ratchet-wheel and pawls, alsoforming part of the turning device.

In all the figures of the drawing, like letters of reference representlike parts.

I will now describe, in detail, the arrangement for moving the valve.which valve, as shown in drawing, is what is called the dou-' bleD-valve, having a movement over the ports parallel with the line ofmotion of the piston.

In Fig. 1, A is the steam or air cylinder, with induction-passages a a,and eductionpassages b b. B is the valve-chest. C is the valve. D iswhat I call the rocker-arm or tripping-lever, which inserts its point ina slotted hole in the arch of the valve. E E are slots in the sleeve F,in which slots the two cams d d of the tripping-lever play back andforth. G G' are pistons, divided by the sleeve F, the whole forming, asit were, one solld piston, although the two ends alone need besteam-tight in the cylinder.

The tripping of the lever D, and with it the valve B, is efl'ected asfollows: The trippinglever D and cams d d are of one piece, vibrating ona center pivot, 6. Each cam alternately projects down into the slottedway out for its reception in the sleeve-piece, the slotted way E beingfor the cam d, and the slotted way E for the cam d. These slotted waysare deepest at their extreme ends, where the points of the cams reachto, and for the purpose of keeping the valve in constant motion thebottom of these slotted ways will form an inclined plane from one end tothe other. As the piston nears the end of its stroke, the slotted waydirectly under the cam, which must then be tripped upward, suddenlyceases curving sharply upward, so that as the cam is thrown up thetripping-lever pushes over the valve, to exhaust the steam or air fromone end of the cylinder and supply it to the other. As one cam istripped up the other cam drops down into its slotted ways, and in turnundergoes the same operation.

It will be observed in Fig. 2 that the slotted ways are cut diagonallyalong the sleeve, instead of parallel with its sides. This is necessarybecause, as the piston advances or returns, the sleeve turns slightlyaround, say about one-sixteenth of a turn--a matter explained below inconnection with'my device for turning the drill, which forms the secondportion of my invention, which I will now describe.

This device consists in providing one or more slotted ways, H, (shown inFigs. 1 and 2,) cut diagonally along t-he sleeve F, at any suitablepoint on its circumference. In this slotted way a pin, h, plays back andforth as the piston moves, the pin being firmly secured in the side ofthe cylinder A. The sleeve F is cut in two partsby a zigzag cut at i,the cut forming, as it were, a series of ratchetteeth on each end of theseparated pieces which join together. Now, the sleeve being loose uponthe piston-rod, when it is revolved in the direction of the arrow-pointto the right hand, Fig. 3, it moves freely between the piston-heads; butif it be revolved in the contrary direction the two parts of the sleevewill spread apart and bind firmly between the heads, because of theinclined faces of the cut at letter i; and then, when the sleeve turns,as it must when the slot H passes over the pin h, the-piston-rod alsomust turn, and with it the drill. Ordinarily, this device will besufficient to effect a turning of the drill; but to avoid any chance ofslip should the two parts of the sleeve not spread apart sufficiently, Icut the ratchet-teeth, as in Fig. 4, inside the small piece of thesleeve at K, Fig. 3, two or more pawls being attached to the piston-rod,as shown in Fig. 4. There will be springs behind the pawls to keep themengaged with the teeth of the ratchetwheel. The effect of these pawlsand ratchet-wheels will be to hold the small piece of the sleeve fromadhering to and turning with the large piece, and will insure theirspreading apart, as before described.

What I claim as my invention, and desire to secure by Letters Patent, isas follows:

1. The combination of the cams d d, rockerarm D, and slotted ways E E,as a means of moving the valve 0, substantially as described, and forthe purpose set forth.

2. The sleeve-piece F, when cut in two by the zigzag cut 1', incombination with the slotted way H and pin h, substantially as and forthe purpose described.

PRESCOTT S. BUOKMINSTER.

Witnesses:

L. E. MORGAN, E1). J. CARPEAUX.

